Controlled power pneumatic impact wrench

ABSTRACT

A controlled torque reversible pneumatic impact wrench for use particularly in mounting the wheels of automotive vehicles equipped with disc brakes is provided with an air regulating valve introducing differential flows of air to the rotor during the forward and reverse drive conditions of the wrench. In the reverse drive condition of the wrench full air pressure is applied. In the forward drive condition thereof, a restricted air volume is applied as required to develop a predetermined maximum torque.

United States Patent [1 1 Hall a 1451 Sept. 3, 1974 [54] CONTROLLEDPOWER PNEUMATIC 3,635,605 1/1972 Hall et a1. 173/169 I P C WRENCH3,666,027 5/1972 Sauerwein et al. 173/169 Inventor:

Automotive Industrial Marketing Corporation, Portland, Oreg.

July 26, 1973 Assignee:

Filed:

Appl. No.:

US. Cl 173/169, 173/163, 415/503 Int. Cl B25b 21/00 Field of Search173/163, 169', 415/503, 415/152; 418/239; 251/207, 209

References Cited UNITED STATES PATENTS 11/1966 Leibfritz et a1. 251/20911/1971 Brown 415/152 Walter Dennis Hall, Portland, Oreg.

Primary ExaminerHenry C. Sutherland Assistant Examiner-William F. Pate,III

[5 7 ABSTRACT 2 Claims, 12 Drawing Figures IE EB I 3.833.068

I sneet NF 2 CONTROLLED POWER PNEUMATIC IMPACT WRENCH BACKGROUND OF THEINVENTION This invention relates to reversible pneumatic impactwrenches. It pertains particularly to controlled torque reversiblepneumatic impact wrenches of the class employed in applying and removingthe mounting bolts used for mounting the wheels on automotive vehiclesequipped with disc brakes.

Reversible pneumatic impact wrenches of adjustable torque are well knownand widely used. Such wrenches conventionally are supplied with forwardand reverse controls adjustable between a plurality of driving torquesin both the forward and reverse direction.

The use of such wrenches is attended by a significant disadvantage whenthey are applied to the application or removal of the nuts to or fromthe bolts used in mounting the wheels on automotive vehicles equippedwith disc brakes. Disc brake assemblies are sensitive to torque and areaffected by the torque applied to the lug nuts used for mounting thewheels.

Sufficient torque must be applied to secure the nuts. On the other handovertorquing warps the rotor of the disc brake assembly and adverselyaffects the operation of the brakes.

For most efficient operation of the brakes, an adjustment tolerance of0.0005 inch must be maintained. Overtorquing of the mounting lug nutscan pull the rotor out of adjustment by as much as 0.012 inch. This notonly affects the operation of the brake, but may permanently damage thebrake parts so that replacement is required.

When using conventional reversible pneumatic impact wrenches for thepurpose of changing a tire, the problem is magnified by the fact that itfrequently is necessary for the mechanic to adjust the wrench to maximumtorque in the reverse setting of the wrench in order to remove nutswhich were overtightened when the wheels were mounted. This settingapplies a torque in the reverse direction which is far in excess of thatwhich should be applied when the tool is used in the forward drivesetting.

Working under the pressure of time, the mechanic then forgets to reducethe wrench torque setting when remounting the wheel. As a consequence,the nuts then are largely overtorqued and the disc brake rotors warpedout of adjustment.

It is the general object of the present invention to provide areversible pneumatic impact wrench of controlled torque in the forwarddrive position, the torque being predetermined to tighten the mountingnuts of automotive vehicle wheels to the precise condition in which theysecurely mount the wheels, but without disturbing the setting of thedisc brake rotors associated with the wheels.

Still another object of the present invention is the provision of areversible pneumatic impact wrench of controlled and predeterminedtorquein its forward drive setting. but capable in its reverse settingof exerting maximum torque as required to loosen the mounting nuts ofautomotive vehicle wheels which have been overtorqued in theirapplication.

Still a further object of the present invention is the provision of areversible pneumatic impact wrench of controlled torque which is selfcompensating in that it delivers the predetermined torque even thoughthe air pressure applied to the wrench varies between wide limits.

Yet another object of the present invention is the provision of areversible pneumatic impact wrench of conventional contour and designprovided with a simple and foolproof torque control.

BRIEF SUMMARY OF THE INVENTION The hereindescribed reversible pneumaticimpact wrench of controlled torque comprises in combination a hollowcase, air conduit means in the case, and coupling means for coupling theconduit means to a source of air under pressure.

A throttle valve is present in the conduit for supplying air on demand.A novel combination reversing and air regulating valve is present in theconduit downstream from the throttle valve.

A reversible air driven rotor is coupled to a rotary wrench and drivenin forward and reverse directions by air supplied through the conduit.An air exhaust port communicates with the conduit downstream from therotor.

The combination reversing and air regulating control valve comprises acylinder equipped with inlet and outlet ports arranged in such a mannerthat in the reversing position of the valve, maximum air flow passestherethrough and hence maximum torque is applied to the wrench. In theforward positionvof the valve restricted air flow is transmitted throughthe valve to the wrench as required to develop a controlled maximumtorque of constant and predetermined value.

THE DRAWINGS FIG. I is a view in side elevation of the presentlydescribed controlled torque reversible pneumatic impact wrench, partlyin section and partly schematic.

FIG. 2 is a fragmentary view in rear elevation illustrating a controlfor the wrench. 7

FIGS. 3, 4, 5, and 6 are detail sectional views taken along lines 33,4-4, 55 and 66 respectively of FIG. 1 and illustrating the operation ofthe wrench in the forward drive position.

FIG. 7 is a fragmentary sectional view corresponding to FIG. 1 butillustrating the wrench in its reverse drive position.

FIG. 8 is a fragmentary view in rear elevation similar to FIG. 2 andillustrating the setting of the valve con trolling the operation of thewrench in the reverse drive position.

FIGS. 9, 10, II and 12 are detail sectional views taken along lines 99,10-10, 11-11 and l2l2 of FIG. '7, and illustrating the air flow throughthe tool with the control valve set in the reverse drive position.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT As viewed in FIG. 1, thehereindescribed controlled torque, reversible, pneumatic impact wrenchis housed in a hollow case indicated generally at 20 and consisting of ahandle 22 and a head 24. Air under pressure is supplied to the wrenchthrough the handle by means of an air line 26 which in the appliedposition communicates with a conduit segment 28.

A throttle valve of the check valve type is controlled by a trigger 32in conventional manner. It serves as an on-off valve in the use of thetool.

Air under pressure admitted to the wrench via conduit segment 28 drivesa conventional air motor rotor 34 coupled to a conventional wrench head36.

The operation of the rotor is controlled by means of a combinationreversing and air regulating valve indicated generally at 40. Itcomprises a cylinder type valve which preferably is formed as a singleintegrated unit, although if desired it may be fabricated from componentparts tied together and working as a single unit.

As illustrated particularly in FIG. 6, valve comprises a cylinder body42 which acts as a bearing in mounting the valve. It has on one end anoutwardly extending shaft 44 to which is pinned a control knob 46.

A diametrically opposed shaft 48 is integrated with the other end ofcylinder body 42, coaxially with shaft 44. It mounts a bearing 50 withintegral head 52. 0- rings 54, 56 seal off the valve assembly.

Valve body 42 is formed with a hollow chamber 58. The chamber isprovided with three ports: two inlet ports and an outlet port whichfunctions in two positions of the valve.

The inlet ports are indicated at 60, 62, respectively, FIG. 3. Inletport 60 is used during forward driving of the wrench. It is ofrestricted size as required to apply a predetermined maximum torque.Inlet port 62 is used in the reversing position of the wrench. It is ofmaximum size as required to deliver maximum torque when the tool isreversed.

An outlet port 64, FIG. 4, communicates with a conduit segment 66leading to the forward drive side of rotor 34. The same outlet port,port 64, communicates with a conduit segment 70 leading to the reverseside of the rotor in the 180 adjusted position of the valve.

There thus are provided two pairs of ports, alternately operable in theforward and reverse drive positions of the wrench. In the forward driveposition, restricted inlet port 60 is coupled to exhaust port 64; whichcommunicates with conduit segment 66. In the reverse drive setting ofthe tool, enlarged inlet port 62 is coupled with exhaust port 64, whichnow communicates with conduit segment 70.

OPERATION The combinationreversing and air regulating valve thus may beset between two positions by operation of operating knob 46. In theforward drive or clockwise position of FIGS. 26 inclusive (position R ofFIG. 2), air under pressure admitted through conduit segment 28 passesthrough restricted inlet port 60 and into chamber 58, enlarged inletport 62 being blanked off. The pressure air then leaves the chamber viaexhaust port 64 and passes through conduit segment 66 to the chamberhousing rotor 34. It is exhausted from this chamber by conduit segments70 and 80, the latter of which communicates with exhaust ports 72, FIG.1.

In the reverse setting of the wrench, indicated by the symbol L of FIG.8, the reverse sequence occurs. This is illustrated in FIGS. 7-12inclusive.

In this setting of the tool enlarged inlet port 62 registers withconduit segment 28 and restricted inlet port 60 is blanked off.

Air under pressure enters chamber 58 via enlarged inlet port 62, andleaves via outlet port 64 adjusted to the position of FIG. 10. It passesthrough conduit segment to the chamber housing rotor 34, driving thelatter in the reverse direction. It exhausts through conduit 66 whichnow connects with conduit communicating with exhaust ports 72.

Thus by a simple adjustment of the control knob it is possible to shiftthe tool between a forward drive position wherein it delivers acontrolled and predetermined torque and a reverse drive position whereinit delivers unrestricted torque determined only by the capacity of thetool.

Having thus described my invention in preferred embodiments, I claim:

I. A controlled torque pneumatic impact wrench comprising incombination:

a. a hollow case,

b. air conduit means in the case,

c. coupling means for coupling theconduit means to a source of air underpressure,

d. throttle valve means in the conduit means for supplying air theretoon demand,

e. combination reversing and air regulating valve means in the conduitmeans downstream from the throttle valve means,

f. reversible air driven rotor means in the conduit means downstreamfrom the combination reversing and air regulating valve means,

g. rotary wrench means coupled to the rotor means and h. air exhaustport means communicating with the conduit means downstream from therotor means,

i. the combination reversing and air regulating control meanscomprising: I l. a rotatably mounted hollow cylinder adjustable betweentwo positions, 2. two inlet ports in the cylinder registrableselectively with the infeed side of the conduit means,

3. rotor forward and reverse drive outlet ports in the cylinderselectively registrable with the outfeed side of the conduit means,

4. one pair of ports comprising one inlet port and the outlet portcommunicating through the conduit means with the forward drive side ofthe reversible motor and the other pair of ports comprising the otherinlet port and the outlet port communicating through the conduit meanswith the reverse drive side of the reversible motor,

5. the said one pair being of predetermined but smaller capacity thanthe said other pair,

6. and adjusting means on the cylinder for adjusting it altematelybetween forward and reverse drive conditions of the rotor.

2. The pneumatic impact wrench of claim 1 wherein the inlet portcomponent of said one pair of ports is of restricted capacitydetermining the air flow through said one pair.

1. A controlled torque pneumatic impact wrench comprising incombination: a. a hollow case, b. air conduit means in the case, c.coupling means for coupling the conduit means to a source of air underpressure, d. throttle valve means in the conduit means for supplying airthereto on demand, e. combination reversing and air regulating valvemeans in the conduit means downstream from the throttle valve means, f.reversible air driven rotor means in the conduit means downstream fromthe combination reversing and air regulating valve means, g. rotarywrench means coupled to the rotor means and h. air exhaust port meanscommunicating with the conduit means downstream from the rotor means, i.the combination reversing and air regulating control meanscomprising:
 1. a rotatably mounted hollow cylinder adjustable betweentwo positions,
 2. two inlet porTs in the cylinder registrableselectively with the infeed side of the conduit means,
 3. rotor forwardand reverse drive outlet ports in the cylinder selectively registrablewith the outfeed side of the conduit means,
 4. one pair of portscomprising one inlet port and the outlet port communicating through theconduit means with the forward drive side of the reversible motor andthe other pair of ports comprising the other inlet port and the outletport communicating through the conduit means with the reverse drive sideof the reversible motor,
 5. the said one pair being of predetermined butsmaller capacity than the said other pair,
 6. and adjusting means on thecylinder for adjusting it alternately between forward and reverse driveconditions of the rotor.
 2. two inlet porTs in the cylinder registrableselectively with the infeed side of the conduit means,
 2. The pneumaticimpact wrench of claim 1 wherein the inlet port component of said onepair of ports is of restricted capacity determining the air flow throughsaid one pair.
 3. rotor forward and reverse drive outlet ports in thecylinder selectively registrable with the outfeed side of the conduitmeans,
 4. one pair of ports comprising one inlet port and the outletport communicating through the conduit means with the forward drive sideof the reversible motor and the other pair of ports comprising the otherinlet port and the outlet port communicating through the conduit meanswith the reverse drive side of the reversible motor,
 5. the said onepair being of predetermined but smaller capacity than the said otherpair,
 6. and adjusting means on the cylinder for adjusting italternately between forward and reverse drive conditions of the rotor.